Peroxisomes are single membrane bound vesicular organelles containing 50 or more matrix enzymes that participate in a wide variety of metabolic processes. The overall goals of this project is to identify all the genes involved in peroxisome assembly and function, to understand the normal biology of their protein products and to elucidate their role in inherited peroxisomal disorders. Specifically, we will continue our studies of the role of PMP70 and related peroxisomal membrane ABS transporters by characterizing the metabolic, cell biological and molecular phenotypes of mice with targeted disruptions of these genes and by directly analyzing the function of the purified transporters in vitro. We will use this knowledge to inform a search for patients with primary defects in the genes encoding these proteins. We will also continue our search for patients with primary defects in the genes encoding these proteins. We will also continue our efforts to define additional genes responsible for the peroxisome biogenesis disorders. Finally, we will focus on the identification of the genes that encode specific small molecule transporters in the peroxisomal membrane. We will use yeast, cultured human cells, mouse models and in vitro studies to determine the functional characteristics of these proteins encoded by these transporter genes. We will use this information to search for patients with primary defects in these genes.